Amphiphilic graft hydrogel containing hydrophobic poly(trimethylene carbonate) (PTMC) oligo segments was synthesized. The graft gel had PTMC segments with a degree of polymerization of either 11 or 21, and the in-feed composition ratio of the graft segments was 2 mol%. Three types of graft gels containing different hydrophilic monomer units as the main chain were synthesized by photo radical polymerization, and their swelling ratios and loading efficiencies of a model drug molecule were examined. The swelling ratio of the hydrogel decreased with increasing feed ratio of PTMC segments and was altered by the presence of hydrophilic monomer units. The hydrogel is cross-linked not only by the chemical cross-linker but also by the hydrophobic domain of the PTMC graft segment. Furthermore, the hydrophobic domain could be used to incorporate molecules such as a model drug. Two types of molecules such as hydrophobic and amphiphilic molecules were used, and the selectivity of the molecular incorporation in each graft gel was evaluated by UV–Vis spectroscopy. Both model drug molecules were incorporated into the graft gel, and an amphiphilic molecule was released from the shrunken gels; however, the hydrophobic molecule remained incorporated. These features are important for hydrophobic drug loading, and hence, the functional graft gels are expected to be useful for selective molecular incorporation.